


the uncertainty principle

by MistressEast



Series: quantum entanglements [2]
Category: Dr. STONE (Anime), Dr. STONE (Manga)
Genre: Identity Porn, M/M, Making Out, Manga Spoilers, Pining, Senku's POV of the observer effect, Texting, Wrong Number AU, cheeky references to sex, don't hide author's style, less science than the last one but there's still science, senku is smart but he's also really really dumb, the boys being oblivious
Language: English
Status: Completed
Published: 2020-07-23
Updated: 2020-07-23
Packaged: 2021-03-05 00:20:02
Rating: General Audiences
Warnings: Creator Chose Not To Use Archive Warnings
Chapters: 1
Words: 15,116
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/25461565
Author URL: https://archiveofourown.org/users/MistressEast/pseuds/MistressEast
Summary: Thirty-seven hundred years after the petrification incident, Senku runs the numbers and finds it unlikely that he'll ever see the stranger he texted again.
Relationships: Asagiri Gen/Ishigami Senkuu
Series: quantum entanglements [2]
Series URL: https://archiveofourown.org/series/1844311
Comments: 30
Kudos: 699
Collections: favourite drst fics





	the uncertainty principle

**Author's Note:**

> i teased it all those months ago and it's finally here! now everyone will know what was going through Senku's head during the events of the observer effect. i didn't want to just retype the same scenes over again, so, rest assured, this is all new, never-before-seen content of our two favorite disasters.
> 
> i don't recommend reading this without first reading the observer effect because this story happens in parallel to that one and you won't get the full experience if you aren't familiar with the first part. 
> 
> i hope you enjoy!

Senku has a lot on his mind.

Truthfully, Senku has had a lot on his mind for thousands of years; between counting and calculations and theories and desperately trying to keep himself conscious, he spent the entire time he was petrified constantly _thinking_ , and his mind hasn’t slowed at all since he woke up.

Once Taiju is free, Senku gratefully closes half a dozen mental tabs to make room for approximately 20 more, because now he can really focus on puzzling out the revival formula instead of simply staying alive. And, not that he’d ever say it out loud, but it’s a relief, having Taiju there, just as block-headed and enthusiastic as always. A brush with the familiar in a strange, alien world.

But no amount of planning or experimenting or frustration or Taiju’s endless chatter can keep Senku’s mind from wandering, despite his best efforts. It happens most often at night, in the dead darkness and silence of the stone world: worries and worst-case scenarios that he barely keeps at bay in the daylight bubble to the surface like a beaker boiling over.

And always, _always_ , his thoughts turn to Ma-ban.

It’s not efficient. It’s not helpful. His bizarre texting relationship is less than irrelevant now and therefore a waste to even think about, but no matter how much Senku scolds himself, the thoughts persist. The _worry_ persists.

The fact that he found Taiju so easily is nothing short of a miracle. The fact that Yuzuriha stayed in the same place for 3700 years is astronomically unlikely. Senku reviving at all was more based on luck than he’d like to admit, so he’s probably fresh out of incredible odds. And it would take _more_ than a miracle to find Ma-ban at this point.

Because there’s simply nothing to find.

They never exchanged names, emails, or addresses. Per their agreement, they never even shared specific details about their lives. At the time, Senku had appreciated the anonymity. Real people were messy and illogical. If things got too real, it was easy to pretend Ma-ban was just a program, a place to go when he needed a reprieve from the real world. It would have been relatively easy to dig up Ma-ban’s identity using their phone number, but Senku never felt the urge. What they had worked for them, a delicate balance of un-knowing and distant intimacy, and Senku didn’t want to tip the scales.

Now, however, he’s never regretted anything more. If he just had _something_ , some clue or hint, a place to start, then maybe—

Every night, it’s the same thing. Rifling through his memories for anything that could indicate Ma-ban’s true identity, coming up empty, drowning in frustration, rinse and repeat until he finally falls asleep. Over and over. Even during the day, he can’t keep Ma-ban out of his head. His hands itch for his phone, used to reaching for it when he needed a distraction, when he was struggling with a complex problem and needed a break, when he felt lonely….

Taiju only brings it up once, painfully, right after they crack the revival formula. As overjoyed as he is at the prospect of getting Yuzuriha back, he still pauses his celebrations to level an inquisitive look at Senku.

“Unless, you want to….” he starts uncertainly. “You know?”

Senku doesn’t look at him. “What do I know?”

“I mean—” Taiju shifts his weight. “Unless you have some idea...where Ma-ban-san—”

“No.”

“I know we haven’t really talked about it, but do you think—”

“Taiju, this isn’t the time,” Senku cuts him off tonelessly. “You want to free Yuzuriha, right? Let’s focus on that.”

“Oh...okay!” Taiju bounces back quickly, but Senku doesn’t miss the searching look tossed his way.

His stomach clenches unpleasantly. This really isn’t efficient.

If he could start to search for Ma-ban, he would, if only to ease the gnawing anxiety in his chest. But he’s stuck: he can’t move forward with nowhere to start but he can’t get his brain to shut up about the whole thing.

So he just relives old conversations, desperately trying to recall something he missed and compiling the small amount of concrete information he has.

* * *

Your job sounds...tough.  
  
Oh, it’s SO tough, sensei. You have no idea.  
  
Yeah, I literally have NO idea.  
  
I know you’re a “performer” but you may as well be an exotic dancer for all that tells me.  
  
Sensei!  well I guess we know what gets your engine running!!  
  
Hardly.  
  
Well, what if I AM an exotic dancer? Will you think less of me?  
  
Are you?  
  
Answer the question! I need to make sure you’re a man who will respect my hypothetical dancing career.  
  
No, I wouldn’t think less of you.  
  
In that case maybe I am. Orrrr I could be a host? Or work in a maid cafe? Any of those work for you, sensei?  
  
Listen, I would never judge your choice of job. Unless you’re a “performer” of bank heists or something.  
  
Oh please, as if you wouldn’t LOVE to get in on that, sensei.  
  
I’m not interested in using my skills to break the law.  
  
As long as the law isn’t in my way.  
  
Oh my. How chaotic neutral of you.  
  
Science is neither good nor evil.  
  
Yes, you’ve said that before. Hypothetically, if you WERE to use your skills on a bank heist, how would you go about it?  
  
And this is irrelevant to your profession?  
  
Of course! It’s just a thought experiment.  
  
Never liked those.  
  
No, you’d rather have a brick-and-mortar experiment.  
  
Science is all about what you can perceive with your senses.  
  
How would you PERCEIVE the perfect bank heist?  
  
I’m starting to think this isn’t innocent curiosity.  
  
What are you gonna do~? Call the police on me~? Oooh~!  
  
You’re lucky this isn’t a brick-and-mortar relationship because I’m positive you would be insufferable in real life.  
  
Well, consider our relationship a thought experiment and give me those bank heist plans, sensei. I’ve got several interested parties on the line.  
  
Okay, so the first step is reconnaissance, as always. You’re going to want to watch your mark for several weeks to learn the patterns. Have you ever heard of the Isabella Gardner museum heist?  
  


* * *

Asagiri Gen is a walking nightmare.

He’s a tangle of contradictions and slick words, prickling under Senku’s skin like the air before a storm, and from the second they meet Senku knows he should brace for impact. So he braces and Gen bowls him over anyway.

With a sly smile and a jagged scar to match, Gen is the first obstacle since Tsukasa murdering him that’s actually given Senku pause. Not much pause, but pause nonetheless. Fortunately, Gen isn’t half as shallow as he claims, and after a few minor hiccups, Senku has secured a new ally for the Kingdom of Science.

That should be the end of his preoccupation with Gen. Uncertainties overcome, tentative loyalty established, teammate acquired, check, check, check, just according to plan. Time to move on to the next problem. And yet. After Gen disappears into the woods, limping resolutely back to Tsukasa’s camp, Senku dwells on the mischievous glint of Gen’s eyes, the coy tilt of Gen’s head, the cold bite of Gen’s sarcasm, and something buzzes at the back of his mind. Something impossible.

Familiarity.

He was passingly familiar with Asagiri Gen, the celebrity magician and author of _Magic Psychology_ , an incredibly trite book that his classmates were briefly obsessed with. He occasionally caught glimpses of the smarmy-looking mentalist on magazine covers or late-night variety shows, but he never gathered a significant reservoir of information about the guy. His wheelhouse was so far removed from mentalism that he never even entertained the barest interest in Asagiri Gen. So why now, having interacted with him for the first time in his entire life, does Senku feel like he _knows_ Gen?

He doesn’t have a lot of time to ponder the situation, too busy bringing modern medicine to the stone world, but he never quite shakes it, and it’s distracting enough to occupy a permanent mental tab in his head, just sitting there, picking at him ceaselessly.

Perhaps he’s just starved for modern company. With Taiju and Yuzuriha gone, it’s admittedly been exhausting trying to speed the villagers up enough to be useful, and even though he was only around for a brief time, having someone else who even vaguely knew what he was talking about was a relief.

That’s probably it, he figures, brushing aside the lingering sense of _knowing_ that pervades his thoughts of Gen. His own loneliness compounded by his glancing association with a mildly-famous personality. That’s all.

And yet, when Gen’s voice rings in his ears, high and clear even over the chaos of the Grand Bout, he responds without a second thought, as though he’s been waiting for Gen to chime in the whole time.

Gen swirls into the thick of things, effortlessly taking control with nothing but a few slick words and a handful of flower petals, and Senku appreciates, for the first time, how truly convenient it would be to have a manipulator around all the time. And later, all it takes is a meaningful look for Gen to realize Senku’s plan and pick up the ruse admirably.

It’s stressful, watching Gen’s distinctive purple robe vanish into the woods alongside Tsukasa’s men, but Senku grapples with another sensation he has no right feeling for someone he’s known for such a short time: faith. He trusts Gen to stay safe, and he trusts Gen to leave them a trail, and he trusts Gen to follow through with the knife he sends through Suika. His trust in the villagers thus far has been mostly born of necessity; if he doesn’t trust them, he won’t get anything done, but the faith he has in Gen is different.

Almost...instinctive.

It helps save the village from complete annihilation, and then Gen is removed from double-agent duties in favor of being a permanent citizen of the Kingdom of Science. It’s fortunate, really. Senku needs all the help he can get, and even though Gen doesn’t have the extensive knowledge base that he does, it’s undeniably helpful to have someone else around who even remotely knows what he’s talking about.

And Gen isn’t _completely_ clueless when it comes to science. He’s adept at identifying plantlife, has a pretty solid grasp of natural processes, and possesses a working knowledge of anatomy. In fact, Senku occasionally finds himself surprised at what Gen knows.

“I had a friend who was _very_ into science,” Gen explains vaguely the one time Senku asks him.

But what Gen excels at is negotiation. Now that Senku is chief, he can easily get the manpower he needs through authority, but sometimes that kind of rough touch is...not preferable. Senku can’t afford to sow resentment among the villagers, and even though he’s the lawful ruler, he’s still an outsider. So when things get tense, Senku quickly finds that he can rely on Gen to smooth things over with a few honeyed words and well-placed promises.

Not to mention, the village kids _love_ him.

“It’s really not that hard,” Gen chuckles, plucking the leather hide from Senku’s hands and scanning it curiously. “Most people are fundamentally the same. Everyone wants to feel safe and in-control. Appeal to that, and you’re usually golden.”

Senku rolls up another hide with some scrapped designs on it. “You learn that through study or experience?”

“Experience, mostly. I did a lot of research when I was writing my book, but you have to get good at dealing with people.” Gen lays the hide flat on the floor of the science shed and looks up. It’s evening, and his pale eyes are picking up the colors of the dimming sky outside. “In my line of work, anyway.”

“Right.”

“You’re always so dismissive of my craft, Senku-chan!”

“Name a time.” Senku can’t resist a smile, pulling the hide back toward himself.

Gen dabs at his eyes theatrically. “It’s just in your demeanor. I can sense it. I’m very good at reading people.”

“Well, then you need more practice, because I think your skills are very useful.”

“ _Useful_ , yes, but you’re not impressed.”

Senku takes a piece of charcoal and strikes through a note he made on the hide. “I’m not one of the village kids, mentalist. It takes more than a few magic tricks to impress me.”

Humming, Gen settles into a more comfortable position, obviously intending to stay a while. “And yet, you always come to watch my shows. _Very_ interesting.”

“Don’t read into things.”

“But that’s my job!” Gen smiles and Senku has to forcefully pull his gaze back down to his notes. “I have to take what I can get with you, Senku-chan. You’re a bit of a cold fish.”

“A what?”

“You play your cards close.” A pale, slim-fingered hand creeps into Senku’s periphery, tracing the boxy lines of what will become the cell phone body. “But not close enough to escape me.”

Senku can't help but glance up at that. “Is that some sort of threat?”

Smiling, Gen drums his fingers delicately against the hide. “Not a threat. Just letting you know. I’m figuring you out, Senku-chan.”

“That _is_ a threat.” Senku goes back to his work, ignoring how his stomach flips. He doesn’t have time to puzzle out whether the reaction is caused by Gen’s words or the way Gen’s eyes glitter in the sunset or the soft, delighted sound of Gen’s laughter, so he elects not to waste the energy and put the whole matter from his mind.

* * *

Do NOT make fun of me.  
  
  
  
Do you need something, sensei?  
  
I’m serious. I’m going to ask you a question and I need complete sincerity in response.  
  
Of course, sensei. I would never dream of teasing you.  
  
What do you know about hair care?  
  
  
  
I’m leaving.  
  
No, wait!  
  
Come back!! I can help you!!  
  
Really?  
  
YES. I was just a little surprised. You don’t seem like the type to give it much thought.  
  
I have...unusual hair. Long story short, the ends are splitting like crazy and nothing is helping.  
  
Unusual how?  
  
Let’s just say the ends are very exposed.  
  
Hmm. Very vague, but okay.  
  
I actually just had some fun salon work done, so I’m knee-deep in hair care. I’m sure I can suggest something helpful.  
  
What kind of salon work?  
  
Some styling and dying. It’s very cute, trust me.  
  
Sure.  
  
Anyway, are you conditioning your hair?  
  
Yeah.  
  
Good. That’s important, but it sounds like just conditioning isn’t cutting it anymore.  
  
I switched to shampoo and conditioner for horses for a while.  
  
That’s not a bad idea! That stuff really works for natural hair.  
  
Nothing really happened.  
  
Hm. And this is a new problem?  
  
Pretty new.  
  
I’m sure you don’t need me to tell you that puberty can change the body in unexpected ways, right Mr. High Schooler?  
  
I’m painfully aware of that.  
  
So it’s probably just your body chemistry changing a little.  
  
Sounds like you should try a hair mask.  
  
I thought masks were for your face.  
  
You can use them on your hair too! They work kind of like a souped-up conditioner. You put some gunk on your hair for a while and then wash it off in the shower.  
  
This sounds fake.  
  
No they really work!  
  
For your problem, you’re gonna take half an avocado, one egg, one tablespoon of honey, and one tablespoon of olive oil, mix them, work it into damp hair, then leave it for half an hour. Then wash it like normal.  
  
Do you really think that will help?  
  
I do! I’ve dealt with crazy split ends before, sensei. And I’m a performer! I always have to look my best.  
  
I admit, this isn’t an area I know much about.  
  
Trust me. Just give it a shot. Once a week for a few weeks. Just see if anything changes.  
  
Think of it like an experiment! You can even keep notes.  
  
That’s not...a terrible idea.  
  
That’s the spirit!  
  


* * *

After Gen climbs out of the observatory, leaving him alone, Senku has a quick mental breakdown.

He’s been so good about not thinking of Ma-ban, too busy to linger on that particular mental scab, so it only follows that Gen would be the one to rip it wide open again. Gen with his ridiculous birthday presents and knowing smile and soft eyes and startling knowledge of astronomy—

When Gen glanced back over his shoulder, gaze catching the glow of the stars, and asked _for what?_ Senku’s mouth had opened on instinct, ready to complete the joke, the stupid refrain he’d passed back and forth with Ma-ban. _For Bohr_. He didn’t even think about it. But it would have meant nothing to Gen, nonsense words that would only serve to drive that particular spike deeper in Senku’s heart. So he bit it back. Played it off.

Now he’s staring blankly at his new telescope as the chill of the night sets in for the first time since he left the cave.

And an insane idea is taking root in his head.

_Sirius B_. Senku recalls the conversation he had with Ma-ban about the star in almost painful detail, and Gen’s words echoed the sentiment a little too well…. What are the odds that—

Senku shakes his head sharply. _No_. The odds are too absurd to contemplate. He doesn’t have time for these speculations, or for the horrible kernel of hope that weasels its way into the persistent haze of despair clouding his thoughts of Ma-ban. Ruthlessly, he smashes the niggling feeling and turns on his heel.

He can’t look at the stars right now.

The road to cell phone communication is long, but the surge of pride and excitement that comes with Chrome’s tinny voice blasting out of their rudimentary speaker is intoxicating. The revelation about his father’s tombstone is similarly exciting, and Gen’s plan, presented with appropriate drama in the middle of the night, makes his heart pound for a variety of reasons.

It’s very on-brand for their sneaky mentalist, and Senku can’t deny the thrill that accompanies plotting alongside Gen, with his crooked smiles and delicate gestures and sighing acceptance of Senku’s wild ideas. The whole thing is risky, and even if it works, he, Gen, and Chrome will be potentially hated by the majority of living humans, but what’s a little bad public opinion compared to saving dozens of lives? Gen, the self-proclaimed shallowest man on Earth, doesn’t even give that aspect a second of pause, so why should Senku?

On the eve before the cell phone team heads out, the village gathers for an impromptu celebration. Senku plays along, pleased with how efficiently they completed the second phone, and even allows Chrome to ply him with a few cups of wine. Not enough to get him wasted, but Senku is undeniably warm and the edges of the world are undeniably soft when he finds himself seated beside Gen on the ground, a little ways away from the reveling townsfolk.

Gen is holding a clay cup of wine in his lap, legs tucked neatly under himself as usual, but he doesn’t seem to be drinking seriously. Probably for the best, since he has an early morning to look forward to. He smiles at Senku when Senku flops down beside him and leans back, bracing himself on his arms with a sigh.

“The jewel sisters are trying to get you drunk,” Gen remarks casually.

Senku snorts. “Thanks, I noticed.”

“They just want you to loosen up a little. Would it kill you to throw them a bone?”

Recalling the three girls’ insistent flirting throughout the evening, Senku shudders. “It might.” He shifts his weight to more properly face Gen. “They don’t really want me anyway.”

Gen purses his lips thoughtfully. “I don’t know—an accomplished, handsome young divorcee in a position of authority? Sounds like the beginning of a romance novel to me.” He smiles, tilting his head. “But I suppose we don’t really have time for that kind of thing right now.”

“Exactly,” Senku agrees. He doesn’t mention the part about how he wouldn’t be interested regardless of the current situation. After a second, all of Gen’s words permeate the film of alcohol over his thoughts and he sits up. “Wait—you think I’m handsome?”

“Catch that, did you?” Gen giggles and reaches up to card one hand through the ends of Senku’s distinctive hair. Senku holds his breath. “Despite this whole...situation up here, you’re a very handsome young man, Senku-chan.”

Senku’s scalp tingles. “Are you drunk, mentalist?”

“Do I have to be inebriated to compliment you?” Gen retracts his hand and takes a dainty sip of his wine. “I compliment you all the time, Senku-chan, don’t be rude. But I am a little tipsy.”

“Right.” Senku swallows. He’s not quite up to analyzing what Gen said but it’s definitely exacerbating the heat in his limbs.

“Is it natural?” Gen asks, gesturing to Senku’s hair. “The green? I guess it has to be, right? Don’t see many salons out here these days.”

Senku runs a hand through his hair, flattening a section briefly only to feel it spring back up as soon as he moves his hand. “Yeah, it’s natural. Who’d ask for green tips?”

“I don’t know. Someone who really likes leeks?”

“Hilarious. What about yours, then?”

Gen hums quizzically, halfway through another sip, and Senku, emboldened by the alcohol, extends a hand and catches the long, white streamer of Gen’s asymmetrical bangs between his fingers. The hair is impossibly silky against his skin and Senku almost misses the way Gen goes rigid at the touch.

“It’s not like this naturally, right?” Senku asks lowly. “I remember the cover of your book.”

Gen clears his throat softly, lowering his cup, eyes darting between Senku’s face and Senku’s hand. “I had no idea you were such a fan,” he teases, sounding a little strangled.

“You wish.”

“You don’t have to play coy with me, Senku-chan.” Gen’s smile is molten in the cast-off light of the bonfire. “But no, I wasn’t born with half-white hair, if you can believe it.” He watches hawkishly as Senku twirls a strand around his finger. “I had it dyed not long before the petrification.”

“Any particular reason?”

Gen shrugs gently. “I thought it might make for more distinctive branding. It’s recognizable, no?”

“I suppose.”

“Anyway, a lot happened after I was revived, and by the time I thought about it, I realized my roots weren’t showing. Even months later. My hair is growing—I had Ruri-chan trim it for me just the other day, but this half is just coming out white.” He frowns. “I guess that is sort of odd now that I say it out loud.”

“Hm.” It _is_ odd, and Senku makes a mental note to keep it in mind when reviving new people. “It might have something to do with how the petrification interacted with your body chemistry. Did you bleach it?”

“Yes.”

“Interesting.” Senku strokes his thumb down the pale strands with renewed curiosity.

“Oh dear,” Gen gasps theatrically and presses his fingertips to his parted lips. “Are you planning to dissect me to solve this mystery?”

Senku huffs out a laugh, finally letting Gen’s hair slide out of his grasp and sitting back. “I doubt I’d get much information from dissecting you. Scalping you, however—”

Gen squeaks in over-blown fear, raising an arm to cover his head and attracting the attention of Suika, who comes rolling over to grab at Senku with tiny fists.

Senku spends the rest of the celebration entertaining her and the other kids while trying to forget how soft Gen’s hair felt.

* * *

Sometimes I wish I had gone to college.  
  
It’s never too late if you actually decide to go.  
  
The dorm life, the boiling kettle of hormones...think of the DRAMA  
  
That’s...not what college is for.  
  
Well, that’s what it’s like on TV. And how would you know, anyway, sensei?  
  
My dad teaches at a college, remember?  
  
Oh. Right.  
  
Well, it’s not like I’d be going for the education part. I just want that DRAMA.  
  
Too much work.  
  
Stoichiometry is all fun and daisies but a little interpersonal drama is too much work?  
  
Yes.  
  
So dull, sensei.  
  
I guess having a parent who worked at a college might remove some of the allure.  
  
What do your parents do?  
  
They were just ordinary salary workers the last time I saw them, but that was yeeeeaaaars ago now, so who knows!  
  
I see.  
  
It’s probably best that I don’t go to college. What if I end up at the same one as your dad  that would be awkward!  
  
How would you even know it was my dad?  
  
I think I’d be able to tell.  
  
You wouldn’t.  
  
I would! I’m a mindreader, remember?  
  
That’s not how that works.  
  
Please don’t question my expertise, sensei.  
  
Oh, I’m so sorry for the disrespect.  
  
You have a definite ~vibe~ that I’m pretty confident I could pick up on irl.  
  
Oh god, what kind of vibe?  
  
It’s not really something I can put into words, sensei. It’s just a ~vibe~  
  
I will say this: it’s very unique.  
  
Thanks, I guess.  
  
Most people just run together to me, sensei, so, yes, you should feel very flattered!  
  
Then I guess I’m flattered.  
  
But anyway I’m sure any parent of yours is at least a fraction as unique as you are.  
  
My dad is definitely...unique.  
  
Do I detect tension?  
  
No, stop reaching.  
  
My dad and I get along just fine. I was being serious.  
  
Okay, okay. Well, I guess I’ll put the college thing aside for right now. I’ll probably be too famous for it soon, anyway.  
  
Right.  
  


* * *

The most troubling thing is that whatever magnetism Senku apparently feels around Gen, Gen obviously feels it too.

After the debacle that was delivering and using the cell phone for the first time, Senku makes the decision to move their main force closer to Tsukasa’s camp, and throughout the whole process, he notices a distinct...it’s not clinginess, from Gen—it’s more like—

Senku really can’t put his finger on it. But whatever it is, it’s evident in the curious way Gen hovers over his shoulder while he drafts, and in the easy way Gen passes over tools and materials with little more than a indicative glance, and in the teasing way Gen allows Senku to help him on and off the bulky, rudimentary car. It’s in the dozens of little things Gen does every day, swaying in and out of Senku’s orbit as simply as breathing, always bringing the subtle scent of flowers and leaving in a swish of purple fabric.

Sometimes Senku watches him go and that clawing familiarity surges so violently it’s all he can do not to snag the back of Gen’s robe and yank him closer.

While Senku works to transform the car into a tank, Gen carries out their plan of impersonating Lillian with aplomb. Thanks to Nikki’s coaching, he’s soon indistinguishable from the real deal, and though he cheerfully attributes it all to his innate talents, Senku frequently overhears him practicing under his breath, repeating singular words over and over until the intonation is exactly what he wants. He only calls Gen out on it once, though.

“You’re supposed to be sleeping.”

Gen jumps slightly, looking over his shoulder. “Senku-chan!” He places his hand over his heart in affected shock. “Don’t sneak up on me like that!”

“I wasn’t being quiet.” Indeed, Senku had made no effort to hide his footsteps as he approached the small rocky outcropping Gen is sitting behind, a little way from camp. “You should be more aware of your surroundings. Don’t want to get stabbed again.”

“Ah—” Gen smiles blithely. “I suppose you have a point. If you get wind of anyone planning to murder me, I hope you’ll let me know.”

“Don’t you think I have enough responsibilities as it is?”

“So cold!”

Senku puts his hands on his hips, smirking. “And those responsibilities don’t include tracking mentalists down past bedtime.”

Unashamed, Gen tilts his head up at Senku. “What do you mean?”

“It’s almost two in the morning.”

“Is it?” Gen peers bemusedly up at the dark sky. Telling the precise hour can be tricky in the stone world, but while Senku’s internal clock is nearly second-perfect, he knows that Gen’s gotten good enough at reading the moon and sun to know how late it is. “Oh dear. I suppose I lost track of my time.”

“Well, cut it out. I can’t afford to have you out of commission.”

“Don’t worry, Senku-chan,” Gen sighs, finally pushing himself to his feet. “I’ll be totally bright-eyed and raring to go in the morning. Besides, it’s not like you have room to lecture me.” Smiling, he prods Senku’s shoulder with one long finger. “You’re up too.”

Senku rolls his eyes, catching Gen’s wrist. “I’m working.”

“I know! You’re always working, Senku-chan.” Freeing his arm, Gen tucks his hands into his sleeves. The cool light of the stars lightens his purple robe to a pale lilac and gleams brightly off the dark half of his hair. Senku notes these details impersonally. “Our fearless leader never takes a break. Though, I guess that’s to be expected. Burning the midnight oil and all that. Ah, if only I could be as dedicated as you—”

“So rehearsing for hours on your own isn’t dedication?”

Gen blinks, all wide-eyed innocence. “I don’t know what you mean, Senku-chan.”

“Then what were you doing over here?”

“So nosy,” Gen scolds. “I’m not beholden to you!”

Senku lifts an eyebrow.

“Anyway,” Gen continues quickly, bustling past him. “Since you’re so invested in my sleep schedule, let’s get back to camp, Senku-chan. I promise I’ll go to bed like a good boy.” He casts a glittering look over his shoulder. “Unless you’d like to supervise me to make sure?”

Against his will, Senku feels his cheeks warm and is grateful for the darkness. “Just get going, mentalist.”

Gen’s laughter rings like a bell as he heads off.

Senku’s not sure why Gen never owns up to the effort he puts into his tricks. Sure, there’s the playful veneer of _real magic_ he puts on sometimes, but in general he seems proud of his practical skills. And yet he’d rather everyone think his impersonations and sleights of hand and _mind reading_ just spring fully formed from his endless well of talents. The only clue Senku really gets is when he watches Gen show off for the kids, practically glowing in the face of their enthusiasm.

Maybe elbow grease just isn’t as commendable in show business as it is in science. And old habits die hard.

Regardless of Gen’s methods, it’s all worth it as more and more of Tsukasa’s people fall under “Lillian’s” spell. And Senku can’t deny that it’s fascinating watching Gen work, the way his whole demeanor shifts between voices, the way he cleverly weaves his words to be as convincing as possible. If Senku needs to step in as a background character, Gen taps quick morse code instructions onto his arm to keep the listeners from getting suspicious, and it’s easy to fall in beside Gen, almost relieving to let someone else lead for a while. Senku enjoys it probably more than he should.

The raid on the Kingdom of Might goes as well as Senku could have possibly hoped. Even that little hiccup at the end wasn’t too far outside of his contingency plans, and through everyone’s combined efforts, they managed to win the day. If he thought that the naturally skittish Gen would panic under Tsukasa and Hyouga’s attack, he’s proven wrong when Gen diligently follows him into the cave for their final stand. But everything happens so quickly, he doesn’t have time to examine the warmth in his chest sparked by Gen’s evident faith in him.

Once they free Mirai, he doesn’t even see Gen again until after everything is over. Tsukasa is resting while Senku mulls over what has to be done, and Gen staggers into the cave. No sarcasm, no doublespeak, just concerned hands and watering eyes.

Senku lets himself lean into it. Just for a minute. The ache in his chest from Hyouga’s failed attack sends his mind back to the sight of the cell phone shattered on the stone, rows of manganese batteries spilling out, tickling something deep in his memory. He didn’t have any particular reason to think Hyouga would betray them the way he did, but a glance at Gen had reminded him that it was always better to be safe than sorry.

So, really, saying that Gen saved his life isn’t an exaggeration.

The first order of business after merging with the Kingdom of Might is freezing Tsukasa. He’s so injured that they can’t delay, and the project takes all of Senku’s concentration. He’s grateful for the others’ help, and that Gen in particular stays nearby, despite his obvious discomfort with the whole process. It isn’t until Tsukasa is...gone...that Senku actually has a moment to consider everything that just happened.

Back in the old days, when Senku needed some perspective or felt overwhelmed, he turned to Ma-ban. Now, he finds himself turning to Gen. They really are similar, Senku muses, folding his arms under his head and squinting up at the blue sky over Tsukasa’s encampment. He’s tucked away near the top of the blocky rock structure that _used_ to feature the Cave of Miracles, lounging against the stone.

Beside him, Gen is listing things he _shouldn’t_ do when he presents his next plan to the newly expanded Kingdom of Science.

“—so don’t bother with the big words; if you can’t explain it in less than a sentence, then just skip it and go back later if people have questions.” Gen sighs, leaning back on one arm and looking down at him. “I know that you’re just going to go with whatever comes out of your mouth, but at least try, alright? If you don’t take my advice on stuff like this, then why am I even here?”

Senku shrugs. “Your paper plane idea was pretty good.”

“Great, relegated to the craft table.”

“Well, what would you prefer?”

“Like, title-wise?” Gen hums. “Deputy? Second-in-command? Maybe vice president?”

Senku chuckles. “We’re not that far along, mentalist. We don’t need titles yet.”

“Hypocrite. You let the villagers call you _chief_.”

“That’s their culture. I’m just being respectful.”

Gen snickers, pressing his fingers over his mouth. “How convenient.”

Squinting against the sun, Senku peers up at Gen. He’s got his outer robe off, enjoying the mild weather in just his yellow slip and high-necked undershirt, and as Senku watches, he tips his head up, letting the light warm his face. “Do you want a title?” Senku asks.

“Oh, not really, I suppose,” Gen relents. “I wouldn’t want to muddy the chain of command. Everyone seeeriously trusts you, Senku-chan, and that’s really special.”

“I wouldn’t say it’s special.”

“But it absolutely _is_.” Gen turns shining blue eyes down at him. “You’ve just absorbed a whole camp of people who were loyal to Tsukasa-chan, not wholly out of fear, and they’re all willing to follow you into the unknown. That’s nothing to scoff at, Senku-chan.”

Senku presses his lips together. “They’re just trying to survive.”

“Well, sure, but following someone out of necessity and following someone out of _trust_ are different. And believe me—” Gen quirks a self-satisfied smile, “—they all trust you.”

“And you know this because you can read their minds, I presume?”

“Yup!” Gen chirps before rolling back, lying flat beside Senku on the stone. Senku follows him down in his periphery. “While I was with Tsukasa-chan, I could tell—some of those folks were just following him because he was all they knew, but he wasn’t a bad leader. He was smart and competent and caring in his own way. A lot of people really believed in him, even if they didn’t necessarily believe in his crusade. To be honest—” Gen reaches his arms over his head and stretches, spine popping, “—Tsukasa-chan is such a force of personality, I suspect you’d have more resistance among our new members if it wasn’t for the fact—” he relaxes against the ground and slides Senku a keen look, “—that Tsukasa-chan liked you so much.”

Senku knows that. It’s plain to anyone with a brain that Tsukasa’s regard is the only reason the transition of power went so smoothly. But hearing it from Gen somehow puts it in perspective.

“When we revive Tsukasa-chan—” Gen continues blithely, “—you two will really be a force to be reckoned with.”

“Yeah,” Senku agrees, a little strangled. “Get excited, mentalist.”

“Oh, I am!” Gen’s mouth turns down in an exaggerated frown. “But Tsukasa-chan is good with people. Maybe you won’t need me soon.”

Senku raises an eyebrow. “Feeling insecure?”

“Just trying to keep all eventualities in mind!” Gen purses his lips up at the sky. “But it’s not like you really need my help now anyway.

“Where’d you get that idea?”

“Please, Senku-chan. You can do anything! If I wasn’t here, you would have figured everything out on your own, don’t pretend otherwise.”

“I’m not going to indulge this compliment fishing, mentalist.”

“Slander!” Gen titters. “Compliments from you _are_ very rare, Senku-chan. I know better than to try and flood the market.”

Shifting onto his side, Senku props himself up on one elbow. “You really want me to say something nice about you?”

Gen blinks up at him. “Senku-chan, I was teasing—”

“Because if that’s what it takes, I can always—”

“No, no, no—” Gen cuts him off, pointing an accusing finger in his face, “—stop trying to make me seem needy—I don’t need your praise, oh venerated leader of the new world—”

“Good.” Senku catches Gen’s indignant hand. “Because you should know without me telling you.”

Gen swallows, and this close, Senku can clearly see the flickering motion of his throat. “Know what?”

Did the sun somehow get hotter? Senku knows that’s impossible, and yet his mind still registers an undeniable spike in his internal body temperature. “How important you are,” he forces out.

Gen stares up at him for a beat, the high sun glinting in the depths of his ocean eyes. Then his face breaks into a wide grin. “Senku-chan, you flatterer! You always know just what to say!”

“I learned from the best,” Senku says quickly before shoving himself to his feet without releasing Gen’s hand, forcing him to scramble upright. “Come on—we’ve got a society to address.”

“Hang on!” Gen protests as Senku starts to tug him down the structure. “I have to meet with Yuzuriha-chan about something!”

“What?”

“You’ll see!”

The _something_ turns out to be a captain’s hat, part of Gen’s bigger scheme to keep the unruly elements of the Kingdom of Science in check. Senku really doesn’t know where Gen’s occasional insecurity comes from; there’s no way Senku himself could handle the potential power struggles as deftly as Gen. And no one knocks Senku out of his own head in the same way.

As they move forward with the newly enlarged Kingdom of Science, Senku is honestly grateful to have Gen at his side, sliding into the gaps of his capabilities. Taiju is his strong arms and tireless energy, Chrome is his eager student and natural encyclopedia, Kohaku is his fierce protector and ready sword, Yuzuriha is his patient ear and steady hands, and Gen…. Gen is his shrewd eyes and silken tongue, his calculated facades and sinuous voice, his sounding board, his partner-in-crime, his moment of respite, the warm body beside him as he works into the night, the first one he reaches for when he needs an opinion or a break or for someone to look at him and really _see_ him—

Gen’s job description grows longer in Senku’s head by the day, and Senku can’t help but think about the last person who came that close. It’s strange, honestly, the way that Gen slips so perfectly into the spaces left by Ma-ban, and, on bad days, it’s enough to make guilt gnaw in Senku’s gut.

It’s illogical to feel guilty, he tries to rationalize. What exactly is he so cut up about anyway? The fear that he’s _replacing_ Ma-ban somehow? What nonsense. The stark truth of the matter is that Ma-ban isn’t here and there’s virtually no chance that they’ll _ever_ be here. Meanwhile, Gen is at his side, whole and real. Nothing can erase what Senku felt for Ma-ban or the relationship they shared, but comparing them to Gen is unfair and damaging, especially when Gen has no idea Senku is mentally measuring him against someone he’ll never even know.

For all intents and purposes, Ma-ban is dead. Even if they’re out there somewhere, the likelihood that Senku will be able to reconnect with them is slim to none. The best Senku can hope for is succeeding in his goal and allowing Ma-ban to be revived and live out the rest of their life, but they will never meet again. He has other things to focus on, other people to support him, but the more he leans on Gen, the more conflated the two become in his head, until his feelings for Ma-ban start to bleed irrevocably into his feelings for Gen and he really needs to shut that down because that certainly isn’t going to help him move on—

Some of his inner turmoil must leak out because suddenly Taiju is sniffing around, bringing up Ma-ban when that’s really the last thing Senku wants to think about right now. He understands that Taiju is just concerned but he’s angry enough with himself as it is and, frankly, he wishes the whole confusing tangle of emotions would just _go away_.

But if Gen’s taught him anything, it’s that people are more ruled by their emotions than they want to admit, and as long as Senku remembers Ma-ban, these feelings won’t disappear. All he can do is push them aside, like always, and try not to wonder how different, or similar, things might be if Ma-ban was at his side instead of Gen.

* * *

I can tell you’re laughing.  
  
I’m not!  
  
You can laugh. I don’t care.  
  
I’m not laughing!! I think it’s sweet.  
  
Pretty sure she didn’t think it was SWEET.  
  
I’m sure she understood, sensei. People don’t confess without being prepared for rejection.  
  
I would like to meet the girl who somehow developed a crush on YOU, though.  
  
You’re trying to insult me.  
  
Never!  
  
But it won’t work. I know you wouldn’t still be talking to me if you didn’t like me.  
  
Oooh~ maybe you’re the mind reader here, sensei~!  
  
Simple observation.  
  
And I’m teasing. You’re an intelligent, sensitive young man, and I’m not surprised girls like you.  
  
Wow, you’re making me blush.  
  
The obsession with science might take some getting used to, but the right partner will support your near-suicidal pursuit of knowledge!!  
  
My experiments are perfectly safe!  
  
What did you say to her, exactly? “I’m in a committed relationship with my centrifuge and we’re not looking for a third”?  
  
A third what?  
  
  
  
I’m just kidding.  
  
Oh, thank god.  
  
I just told her I didn’t feel the same and wasn’t looking for a relationship.  
  
Concise and to-the-point. Very like you, sensei!  
  
Dating in high school seems like a waste of time anyway.  
  
...you didn’t tell her that, did you?  
  
Why?  
  
Sensei! You can’t trivialize a maiden’s pure heart like that!!!  
  
I didn’t say that. But I do think it.  
  
Honestly, I think you’re right. High school is stressful enough, why add to it?  
  
I had PLENTY of offers in high school, but I was too busy starting my career to worry about any of that.  
  
Sure.  
  
Which part are you skeptical about, sensei? The idea that I’m desirable or the idea that I started working in high school?  
  
The idea that you didn’t date anyone.  
  
Why is that so unbelievable?  
  
You know why.  
  
I assure you, I don’t~  
  
You act like you know a lot about relationships. Is that all bluffing?  
  
I’ve studied psychology and human behavior for years, sensei. I don’t need first-hand experience to know that stuff.  
  
Should I be flattered that you think I’m so desirable?  
  
When did I say that?  
  
You implied it~  
  
You come across fairly...flirty. So I assumed you’d at least dated before.  
  
I’ve had a few short dalliances, but I wouldn’t call any of those proper relationships. And they were mostly for networking purposes.  
  
Sleeping your way to the top?  
  
Sensei!  So crass! I would never!!  
  
You wouldn’t take a good opportunity if it presented itself?  
  
Not like THAT! No shade on people who do it, but I have confidence in my own methods.  
  
I see.  
  
Attention is nice, and I’ve got plenty of that, believe me, but I’m a little old-school when it comes to dating. Is it so wrong to want a little ~romance~?  
  
No.  
  
You feel the same, right, sensei?  
  
In a manner of speaking. I want there to be a connection. I wouldn’t want to date a stranger.  
  
Hypothetically, of course. I’m not interested in that kind of thing right now.  
  
Oh, I know that. But there’s nothing wrong with thinking about it.  
  
Right.  
  


* * *

Ryusui is a valuable arrow in Senku’s quiver.

Determined, clever, enthusiastic, and a master of his craft—Senku couldn’t have asked for a better captain. He proves his worth instantly at the shipyard, and Senku wastes no time asking Gen what he thinks of their newest member.

“He’s greedy, that’s for sure,” Gen sighs, wringing out the dripping ends of his hair. They’re huddled in one of the temporary tents in the shipyard, riding out the tail end of the storm after securing their materials. “Oil, huh? And I have no doubt he’ll try to leverage his skills to gain something from us.”

Senku finishes kindling the small fire in the center of the tent, not enough to fill the small space with smoke, just a few embers to ward off the chill of the rain he can hear pounding outside, and swipes his own damp hair out of his eyes. “Oh, he absolutely will. Ten billion percent.”

“And I guess we’ll just have to bow to his demands.” Gen settles on his knees, regarding Senku thoughtfully. His outermost robe is off, drying on the ground beside him. “We’ve played our hand, as it were, by choosing him. That was the last of our revival fluid, so we just have to make the best of it. Not that I was involved in the decision or anything.”

“Don’t stress, mentalist. We’ll make it work.”

“Who’s stressing? And you don’t get to say that stuff—you’re not the one who’ll be contending with Ryusui-chan’s willfillness.”

“Right, right.” Senku crosses his legs and leans his head on one hand. “Make sure to trap him in your mental web or whatever.”

“Well, if you insist.” Gen snickers and Senku can’t resist a small smile. Ryusui is probably expecting some form of manipulation, but he won’t know what hit him when Gen gets started. “But he’s really not so bad,” Gen continues.

“Is that your professional opinion?”

“I suppose. Like I said, he’s greedy, but he’s not malicious. His first instinct upon waking up was to write a check in thanks, right? I’m willing to bet that avarice of his is mostly a front.”

“You think he’s lying?”

“Not lying, but—” Gen tilts his head, the low firelight warming his pale skin with a faint honey glow. “Just wait. It might be a little hard for poor folks like us to understand how Ryusui-chan’s brain works, but I think his obsession with possessing things stems from a deep protective instinct. He’s a provider, but he’s so bombastic and over-the-top that it comes off as entitlement.”

Senku blinks. “You’ve really got his number, huh? How’d you get all that from meeting him once?”

Gen raises his hand to his mouth, smiling slyly. “It’s what I do, Senku-chan. How quickly you forget.”

“Right.”

“He’ll be an interesting element around camp. You might have to bid the title of most eligible bachelor farewell, Senku-chan!”

That brings Senku up short. “Why?”

“Well, Ryusui-chan is very strapping, don’t you think?” Gen taps his chin. “Tall and muscular. And his face isn’t half-bad. He might take some of the heat off of you.”

“I hadn’t really considered that.” Inexplicably, Senku can feel his vaguely positive impression of Ryusui souring rapidly. “I wasn’t thinking about his...face when I depetrified him.”

“It would be good, right? I know you don’t particularly enjoy the attention you get.”

“Yeah, sure, Ryusui is welcome to it.” Senku waves his hand dismissively. He doesn’t care about his popularity or desirability or whatever. So then why does his stomach feel like it's tying itself in knots?

Gen heaves a theatrical sigh. “Between you and Ryusui-chan, I suppose I really should give up my harem dreams. And we’ll wake Tsukasa-chan up eventually too. Such a shame.”

“You were serious about that?”

“Well, no. But it’s a good line, right?”

Senku rolls his eyes.

“I wouldn’t know what to do with a harem anyway,” Gen confesses. “I’ve never been in a relationship. But don’t tell anyone that, Senku-chan!”

“My lips are sealed.” Something taps at the edge of Senku’s memory, but before he can grasp it, Gen is scooting around the fire, shuffling into Senku’s radius with a shrewd look in his eyes.

“And what about you?”

“Me?” Senku repeats dumbly.

“Since we’re sharing romantic tales—”

“ _Sharing?_ Since when—”

“You owe me yours.” Gen’s eyes gleam in the firelight. “Go on, then.”

Senku frowns. “There’s nothing to tell.”

“Don’t be shy.” Gen gestures expansively at the interior of the small tent, lit by dim, jumping light that throws shadows into the folds of their bodies. Outside, the rain is still going strong, a steady patter that encloses them as much as the angled walls. “This is the perfect environment for sleepover stories! You’re such a mystery, Senku-chan, I’ve just _got_ to know—”

“I’m serious,” Senku cuts in, heart squirming unpleasantly in his chest. “I’ve never dated anyone. I’ve never been interested.”

“Oh, I know that.” Gen clicks his tongue and leans sideways into Senku, like they’re sharing a secret. “It’s seeeriously obvious that you’ve never dated anyone. What I’m after is your _type_ , Senku-chan! If you had to choose, what kind of girl would you go for? Or, pardon me, what kind of person?”

Senku swallows dryly. “I really don’t think about that kind of thing.”

“Well, give it a shot. I won’t tell a soul.”

“Mentalist—”

“Oh, _please_ , Senku-chan! Gossip with me! We’re all alone in this tent and we haven’t been alone together in _weeks_.” Gen flashes him a pleading expression. “If you had to spend the rest of your life with someone, what would they have to be like?”

When Gen gets like this, you can either fold or suffer some sort of passive aggressive revenge later, and Senku really isn’t in the mood to have the mentalist’s ire hovering over his head, so with an irritated huff, he actually considers Gen’s question. “Setting aside the fact that I’ll probably be spending the rest of my life with all of _you_ while we rebuild society, I guess….” Senku furrows his brows, extending one finger in front of his face as a focus point, trying to picture every quality he finds desirable in the physical space before him. “I would want someone intelligent—they don’t have to have my exact skillset, but they need to be able to keep up with me. And they have to be independent; I want someone I know can take care of themselves, with their own goals and ambitions.”

In his periphery, he sees Gen shift and can feel the intense weight of Gen’s direct gaze on the side of his face.

“And I value curiosity and drive more than anything else, so any partner of mine would have to feel similarly,” Senku continues, actually kind of getting into it. He doesn’t think about this kind of thing very much, because it’s not like dating is a priority in the stone world, so it’s a new puzzle for his brain to work out: fitting together his ideal partner. “And they have to be willing to learn and make mistakes, because that’s what science is all about. But the most important thing is trust—” Senku retracts his finger, lowering his hand and staring into the fire. “In the end, I can’t have an equal relationship with someone I don’t trust implicitly.”

Gen is quiet for a few beats and when Senku glances over he’s wearing a deeply thoughtful expression.

“Something to say, mentalist?”

“Oh, no!” Gen hitches up his smile. “Just appreciating the amount of planning you put into even something like this!”

“Well, if we’re talking about the rest of my life, it’s not a decision to be made lightly.”

“I couldn’t agree more.” Gen turns to face the fire, the low light glimmering in his eyes. “Still, that’s quite a list. I wonder if there’s anyone out there who can meet those qualifications.”

_Maybe someone, but I’ll never find them_. “It doesn’t matter.” Senku turns to face the fire as well. “Like I said, I’ll probably spend the rest of my life with all of you, doing this.”

“Not interested in repopulating the world?”

“The world’s _already_ populated.”

“Right, right, of course.” Gen leans sideways, knocking his shoulder against Senku’s. “I notice you didn’t mention anything about looks. I assume that kind of thing is unimportant to a logical genius like you!”

“Yup,” Senku says, popping the _p_. “Couldn’t care less how they look.”

“As long as they fit the rest of your incredibly specific qualifications.”

“What about you, then?” Senku cuts his eyes to the side. “What’s your ideal partner?”

Gen’s profile is half-hidden behind his bangs, but Senku can see enough to make out the way his lips purse. He lowers his head slightly, allowing his hair to swing forward and obscure his entire expression.

“Gen?”

“Someone hot, of course!” Gen chirps, straightening up and aiming a pointy smile in Senku’s direction. “You might not care about looks, but _I_ do! I couldn’t stand spending the rest of my life with someone who isn’t _at least_ as beautiful as I am!”

Senku blinks.

“But, of course, that’s an unfair requirement,” Gen goes on, shoulders slumping. “Who could possibly compare? Our little kingdom does have some unique beauties, but none of them _quite_ make it. Don’t you agree, Senku-chan?” Fluttering his lashes, Gen fixes Senku with an entreating gaze, and Senku’s throat abruptly tightens.

He swallows with some difficulty. “No comment.”

“Boo!”

“Anyway, weren’t you the one just talking about how handsome Ryusui is?”

“Oh, sure, he’s good-looking but—” Gen raises one hand and tucks his bangs behind his ear, “—he’s not my type.”

Senku forcefully rips his eyes away from the sight of Gen’s slender fingers sliding over his pale hair. “Too male?”

“Oh, no, nothing like that.”

Senku squashes the hope that flickers in his chest without mercy.

“Well, that was interesting!” Gen says suddenly. “I sure learned a lot about you, Senku-chan.”

“Yeah, and I’m sure you’ll find some way to use it against me.”

“Your distrust wounds me!” Gen’s sharp smile softens. “Besides, when have I ever gotten one over on you, Senku-chan?” Before Senku can answer, Gen starts digging around in the folded front of his yellow robe, shuffling around to face him. “Anyway, the storm’s still on—” he produces his deck of cards and wiggles it gleefully, “—how about a game?”

“Seems like anything we play will be a little uneven, don’t you think?”

“Don’t be so suspicious! This will just be for fun, I promise. No funny business.” Gen lays the cards on the ground between them, swiping them all into a single row with a practiced motion. “And maybe I can teach you some of my tricks.”

“Pass.” But Senku still turns to face Gen, watching him deftly shuffle the cards. “But I guess a few games can’t hurt.”

The smile Gen shoots him is blinding.

* * *

A human baby has about 100 more bones than a human adult.  
  
Good morning to you too, sensei!  
  
I didn’t know baby fever manifested so...morbidly.  
  
I do not have “baby fever.”  
  
Then what brought this on?  
  
One of my father’s coworkers had a baby recently and he made me go see it when she brought it to the school.   
  
Oh no, that sounds terrible! No wonder you distracted yourself by counting its bones.  
  
Yeah, I stuck that little sucker right under the x-ray machine and blasted it with radiation.  
  
You gotta irradiate them young, you know. Maybe you gave it super powers!  
  
Definitely.  
  
But back to the point (?), how can babies have more bones than adults? I haven’t checked recently, but I’m prettttyyyy sure I’m bigger than a baby.  
  
Their structures are the same, but they have about 300 different bones at birth, some of which will fuse as they age until they’re left with 206. The “additional” bones are separated by cartilage and give the baby extra flexibility.  
  
For all of those baby gymnastics they do, right right.  
  
No, so that they don’t get crushed in the birthing process.  
  
Yes, I figured that, sensei, I was joking.  
  
And that’s fascinating, I suppose. The human body is a miracle.  
  
The human body is a dumpster fire.  
  
Oh.  
  
Human young are born nearly a month before they’re technically ready because the mother wouldn’t reliably survive more than nine months of pregnancy. Not a very efficient system.  
  
Oh yikes  that certainly doesn’t inspire me to want children.  
  
Is that something you have to worry about?  
  
Well, the whole process and everything that comes after it sounds like a lot of work   
  
I don’t dislike kids, but having my own? Not appealing.  
  
Ditto.  
  
I’m trying to imagine you holding that baby, sensei, and lemme tell you, it’s pretty funny.  
  
I know how to hold a baby.  
  
Firmly, with a hand on either side of its shell, like a hamburger.  
  
  
  


* * *

Currency existed long before the invention of paper or metal money, even before what might pretentiously be called _civilized society_. Humans have always traded with each other, whether it be food, medicine, seeds, animals, or information; exchange has been a part of human culture since the very beginning, so Senku isn’t panicked about the reintroduction of capitalism, necessarily, but he makes a note to keep an eye on it. The last thing he wants is for greed to start getting in the way of the Kingdom’s ability to work cooperatively, and if he lets things spiral out of control, Tsukasa won’t be pleased when he gets back.

Fortunately, despite his initial pompousness, Ryusui is actually a pretty good guy. Gen really pegged his greed coming from an almost paternal instinct, and even though he’s loud and technically grifting them, the other citizens warm to him quickly.

“Senku!” the now-familiar, beaming voice jars Senku from his concentration and he looks up from the frame of what will soon be Yuzuriha’s new loom as Ryusui comes charging into the hut. “Kujaku told me that you haven’t met Pearl yet!”

Of course, Senku knew that Kujaku had a baby recently, but seeing as he was kind of busy building the hot air balloon and the whole thing had gone off without a hitch, Senku hadn’t felt the need to stick his nose in. But now Ryusui is presenting him with a tiny bundle while Kujaku trails behind him, looking apologetic, and Gen, who had been fixing one of the thread-making tops, gasps in affront.

“Senku-chan! You haven’t been to visit your newest citizen? I’m surprised at you!”

“I’ve been a little busy,” Senku mutters, even as he begrudgingly accepts the baby from Ryusui’s arms.

“Sorry, chief,” Kujaku starts. “I mentioned it to him and he insisted on coming right away.”

“It’s fine—I should have come sooner.” Cradling the newborn carefully, Senku peers down at her squished face and she peers back, looking less than pleased. “I’m glad you’re both healthy.” Truthfully, Senku had been anxious about Kujuaku’s impending due date. Outside of the antibiotics, they’ve been lucky on the medical front so far, and if something went wrong, Senku isn’t confident he’d be able to react in time. But Kujaku is clearly fine, and her daughter is already scowling like she hates Senku’s guts, so his worries were for nothing.

“She just gets grumpier every day,” Gen observes, peeking over Senku’s shoulder. “Cheer up, Pearl-chan! You’re living in the new world!”

At the sight of Gen’s face, the baby perks up and Senku tightens his grip as she starts squirming. “I think she wants you.”

Kujaku chuckles. “She really likes Gen.”

“Like to pull on my hair, you mean,” Gen sniffs, but he holds his arms out for Senku to transfer the baby anyway. Indeed, as soon as he takes hold of her, she frees one of her chubby fists from her blanket and latches onto the trailing end of Gen’s bangs. “—ow! She has—quite the grip, Kujaku-chan.”

“Already reaching out and taking what she wants at such a young age.” Ryusui snaps his fingers, looking inordinately pleased for someone who has no stake in the situation. “Kind of reminds me of me!”

Kujaku grimaces but Senku is distracted by the sight of Gen cooing over the wiggling bundle. “So you’re good with kids _and_ babies.”

“Humans are humans, Senku-chan.” Gen gently disentangles Pearl’s hand from his hair. “And all humans like pretty things.” He preens as his finger is captured in Pear’s little waving hand.

“So humble.”

“You know, someone told me once that babies have three hundred bones at birth.” Gen purses his lips. “So I guess Pearl is even _more_ human than we are.”

While he snickers at his own joke, Senku feels his stomach sink.

Turning quickly back to his work, Senku tosses over his shoulder: “Anyway, I’m glad you and the baby are okay, but we are in the middle of something.”

“Of course.” Kujaku reclaims her daughter and leads a grinning Ryusui out of the hut.

Gen sighs. “Such a taskmaster, Senku-chan.”

“Hm.”

“Not a fan of babies?”

“What gave you that impression?”

“The way you were holding her—” Gen giggles, drifting back to what he was doing. “Like she was going to bite you.”

Senku focuses on the joint under his hands to minimize the anxious churning in his chest.

Sometimes, Gen does that. Says things that make Senku _think_. Ever since the moment in the observatory, Senku has struggled to avoid thinking that way, but if there’s one thing Senku can’t do, it’s _not think_.

Senku has an eidetic memory, and even after all this time, he still finds himself mentally flipping through his interactions with Ma-ban for possible clues, so every time Gen mentions something like that, it lights up his brain like a switchboard. Little turns of phrase, random facts—it’s stuff that anyone could know, but for some reason, in Gen’s mouth, it grabs Senku’s attention and doesn’t let go. The uncanny similarities haven’t slowed since the moment in the observatory, and, in his lowest moments, Senku finds himself cataloguing Gen and Ma-ban’s points of commonality.

They’re both in show business. They’ve both written a book. Neither of them went to college. Neither of them have been in a relationship. They both had their hair styled shortly before the petrification. Plus, they use similar speech patterns and Gen occasionally repeats facts that Senku distinctly recalls sharing with Ma-ban.

However, if there’s something more pointless than comparing Gen to Ma-ban, it’s wishing that Gen _is_ Ma-ban.

The odds of that are beyond ridiculous. Out of every Japanese-speaking person in the world, the chances that Senku would text a minor celebrity and then meet back up with that same minor celebrity more than 3,000 years after an apocalyptic event—Senku doesn’t even need to do the math to know the idea is next to impossible. All of Gen and Ma-ban’s resemblances can be explained by the law of large numbers. The Japanese population can undoubtedly support at least two people with all of those characteristics.

There’s no denying that Gen and Ma-ban are similar, but them being strangely alike is more probable than them being the same person.

* * *

Stop freaking out, it’s nothing bad.  
  
The truth about vitamins is that most vitamin supplements that people take are unnecessary. Vitamins are just substances that the body needs in very small amounts that it can’t generate for itself. If you eat a normal diet, you’re getting all of the vitamins you need, unless you have a medical deficiency.   
  
Sensei, it’s been hours! You made me think I was poisoning myself or something!  
  
I mean, you CAN overdose on vitamins. The body actually can’t store most vitamins, so too much probably won’t kill you, but you really only need VERY small amounts.  
  
I take a multivitamin. Is that okay?  
  
It’s not going to hurt you, it’s just probably not necessary. The vitamins people usually need more of are vitamin K and vitamin D.   
  
I also take a hang on lemme check  
  
I also take a B12 supplement because my doctor said I have anemia :(  
  
Yeah, if you have a deficiency, you should follow your doctor’s instructions. Ironically, with the increased choices in our modern diets, some people choose to abstain from foods they might actually need. Vegans sometimes have to take supplements, for example. You should eat more fish.   
  
I’ll keep that in mind!  
  
The history of vitamins is actually pretty interesting. Before humans knew about the importance of a balanced diet, a lot of populations survived on a limited number of staple foods, and when people started displaying signs of vitamin deficiency, no one knew why. They just thought it was a normal disease.   
  
Oh, like scurvy on ships!  
  
Right, and rickets in children.  
  
Speaking of scurvy, Japanese seafarers rarely had to deal with it because most of Asia knew that certain foods would prevent it as early as 406 CE. Westerners “discovered” and then forgot how to cure scurvy multiple times, despite seeing the evidence over and over. James Lind finally proved citrus was effective in 1747 by performing one of the first controlled clinical trials in the history of medicine.   
  
But even THAT wasn’t enough and it took until 1800 for the west to actually start using citrus to prevent scurvy.   
  
But they didn’t know about vitamins yet, right?  
  
Right. They didn’t know why it worked, just that it did.  
  
Such a tragedy, to live without the light of science.  
  
They got around to it eventually.  
  
It’s so interesting how people can gain knowledge and then lose or ignore it and set themselves back unintentionally.  
  
The path of innovation isn’t always linear, and scientific research sometimes requires lots of people with different worldviews working together. Asian scientists weren’t interested in figuring out WHY citrus worked, since they had plenty of access to fresh fruit and vegetables so it wasn’t pressing, and it took two scientists from Norway trying to find a solution for arctic explorers to finally find the missing piece that would lead to understanding why scurvy occurred.  
  
Necessity is the mother of invention.  
  
Exactly.  
  
Well, I’m glad I live in a time where I can take a pill and make my blood cells behave.  
  
Small miracles.  
  


* * *

Regardless of Senku’s inner turmoil, progress marches on, and it’s a bit of a trip seeing Yuzuriha laying out “modern” clothing, humming blissfully. She tries to cajole Senku into modeling for her, but he waves her off, too busy calculating how to price the pieces and hit Gen’s promised amount.

Interestingly, Gen also declines when she asks him. Senku would have thought someone as outwardly vain as Gen would jump at the chance to show off, but he seems content to hang back and watch. In fact, for a former celebrity, it’s a little odd how _much_ Gen seems to prefer laying low. When given the choice, he chooses to stand behind Senku, manipulating things from the sidelines. Other modern folks strive for some degree of normalcy; Minami noses around and commands attention, while Ryusui actively pursues the reestablishment of his empire—but Gen falls readily into his new role as an advisor, forsaking his previous notoriety with apparent indifference.

These observations don’t lead to a conclusion, but Senku does file the information away for later.

Thanks to everyone’s hard work and some of Gen’s scheming, the hot air balloon is soon complete and ready for flight. Gen seems excited all the way up until the final moments before liftoff, when Ryusui nudges Senku and glances pointedly over at where Gen is standing, face blank, to the side. Senku sends Ryusui an unimpressed look in response. As if he doesn’t already know that Gen isn’t happy.

Gen hitches his smiles up for Senku, though, like always, and when they part, the memory of Gen’s hand in his lingers more prominently than the familiarity of Gen’s words.

The next time Senku sees Gen, as in properly sees him as opposed to speaking with him on the phone, he has to swallow what feels like a literal wave of warmth, but even that isn’t enough to keep his happiness from leaking through, and Gen’s answering smile, exhausted as it is, slots perfectly into a space in Senku’s head that he didn’t even realize was empty.

He’d gotten so used to having Gen at hand that this, their longest separation since Gen left Tsukasa’s ranks, wore on him in ways he wasn’t even aware of until Gen’s presence lifted the burden.

With this in mind, Senku does his best to arrange for Gen to travel with him when he has to change locations. It’s not like he’s making up reasons; usually when Senku is going somewhere in the Kingdom, it’s for problem-solving reasons, and Gen is instrumental in his ability to manage their human resources. So keeping him nearby makes logistical sense.

After their mysterious morse code missive, the shipbuilding efforts grind into overdrive, and Senku finds himself bouncing frequently back and forth between the shipyard, the mine, the oilfield, and the village, sometimes in a group, sometimes with just Gen for company.

Like now, as he guides the speedboat along the coast toward Ishigami village, Gen is his only passenger, and if he glances over, he’ll see Gen leaning over the side of the boat to trail his hand through the water.

“So you’ll drive a boat, but not a car?” Gen asks, words nearly lost to the salty wind whipping past them.

“Fewer things to hit out here, mentalist.”

“Ah, yes, I forgot about all of the other motorists on our one road.” Gen settles back in his seat properly, squinting up at the bright sky. “You handle the boat well, though. Did someone teach you?”

“I lived near a park with a big lake—” Senku steers the boat toward the village’s little inlet. “I used to take a rowboat out with Taiju to do buoyancy experiments, and one day this old fisherwoman offered to take me out further on her boat. I learned by watching her drive.”

“How wholesome!” Gen squeals, clapping his hands. “Ah, the inherent decency of humanity. It’s always so refreshing.”

Senku shoots Gen a crooked smile. “I didn’t just spontaneously develop my skills. I’ve had a lot of teachers in my life.”

“Oh, I never doubted that.” Gen props one elbow on the side of the boat and switches his gaze to Senku. “And now you’re teaching all of us.”

“Guess so.” Cutting the power, Senku guides the boat toward the rudimentary dock built into the craggy shoreline near the village’s island. “What about you?”

“Moi?”

“Who taught you magic? Your parents?”

Gen blows out a scoff, rolling his eyes. “Not even a little. My parents were _not_ supportive of my lifestyle choices. I hadn’t even seen them for years before the incident.”

Senku furrows his brows, and the list of Gen and Ma-ban’s similarities that haunts Senku’s every waking hour grows a little longer, but Gen continues before he can formulate a response:

“I’ve had a few mentors over the years, though. I studied in America for a while. But my style is all me.” He winks and flashes a peace sign. “The patented Asagiri method!”

“Right, sure.” The boat lurches a little as Senku brings it to a stop, bobbing in the water, and he quickly throws a rope over one of the dock posts to anchor them. “How to lie, cheat, and scheme your way to the top.”

“Precisely!”

Senku climbs out first and turns to offer Gen a hand up so that he doesn’t trip on his hem. “I didn’t know about your parents. That sucks.”

Accepting Senku’s hand, Gen steps out of the boat and finds his footing on the wooden boards, shaking his head. “It’s nothing as tragic as what you’re imagining, Senku-chan. I was never on the street or anything. But we aren’t all as lucky as you when it comes to supportive parental figures.”

Senku’s chest gives a hollow pang. “That’s true.”

Eyes slitted like a cat’s, Gen raises one sleeve to cover his smile, and Senku realizes that their hands are still joined. He lets go quickly.

“Anyway, let’s go see Francois.”

“Lead the way, Senku-chan!”

Along with their other skills, Francois’s culinary expertise is a welcome addition to the Kingdom, and Senku still flushes with pride at the memory of his friends tasting _real_ food, some of them for the first time in their lives. Now, Francois is experimenting to find the best combination of factors to make their fruitcake last as long as possible, and a different kind of flush rises to Senku’s face at the sound Gen makes as he samples the most recent attempt.

“ _Very_ impressive, Francois-chan,” he praises, stuffing the rest of the bread in his mouth.

Francois bows demurely. “Thank you. I think this might be the most optimal version so far.”

Senku can’t help but agree. “Good work.”

With another small bow, Francois excuses themself from the cooking area, leaving Gen and Senku alone.

Gen shoots their retreating figure a suspicious look, but quickly turns back to Senku. “I must say, I’m glad we’ve finally expanded the Kingdom of Science’s palate,” he admits.

Senku pops another piece of bread into his mouth. “What, was the ramen not enough for you?”

“Oh, the ramen was _lovely_ —” Gen rolls his eyes. “And the cola, of course, makes my heart skip just thinking about it. But the constant fish was making my hair oily.”

“I don’t think that’s how that works.”

“Trust me, it is. I suppose it wasn’t that bad, though.” Gen glances out at the glittering sea stretching around the island. “I’m lucky to have lived in a place with easy access to fishing.”

“Why’s that?”

“Well—” Gen flips his bangs out of his eyes, “—back in the old days, I had what was colloquially known as anemia.” He chuckles. “Obviously, I don’t have any of my modern supplements, but I was told fish would help, and I haven’t had any problems, so!” Shrugging, he tucks his hands into his sleeves. “All in all, it could be worse.”

Against his will, Senku’s brain adds _has anemia_ to his spiteful list. “Why didn’t you tell me you had a medical condition?”

“It’s not like it’s ever bothered me. I didn’t even know until my doctor told me.” Smiling, Gen pats Senku on the arm. “Don’t worry. If I thought it was going to indispose me, I seeeriously would have been sure to mention it.”

“Anything else you’ve been hiding?”

Gen goes still, eyes trained on the table in front of them, and a little warning sounds in Senku’s head.

“Gen?”

“Nope!” Gen perks up suddenly, beaming. “Unless you count my secret petrification powers that I used to turn humanity to stone!”

Forcing himself to relax, Senku grabs another piece of bread and shoves it in Gen’s grinning mouth. “I knew about those already.”

As the shipbuilding starts getting more complicated, Senku can’t always avoid separating from Gen, however. Different situations require different, simultaneous handling, and Senku occasionally has to split his resources. They keep in constant communication through the phones, but it’s just not the same.

Additionally, something about Gen seems...a little off these days. Most of the time, he’s completely normal, teasing and snide, but sometimes Senku catches a strained smile or forced laugh. Senku would be the first to admit that he’s not really the most emotionally available person in the world, and he doesn’t always pick up on those kinds of nuances in other people, but there are exceptions, people he knows well enough to read them like a language. Taiju, Yuzuriha, Chrome—Gen.

But it’s not like he can just ask Gen what’s up. Not only would Gen absolutely lie to him, but Senku’s not even sure how to go about articulating his misgivings. He can’t point to any specific incident to justify his suspicions, and without evidence, a theory is just a fairytale.

“—and the new furnace is _huge_ —” it’s hard to keep the excitement out of his voice, scanning the photos spread in front of him on the table. “It’s a little unwieldy, especially with only me and Kaseki really knowing how to work it, but we need to start producing higher quality metal. And tomorrow, I think I’ll be done with the new lathe—”

On the other end of the line, Gen chuckles. “You’ve been busy.”

“Unbelievably.” Through the window of the telephone hut, Senku can see the bustling shipyard. As he watches, Ryusui marches past, speaking quickly to Francois, who’s balancing several sacks in their arms. “I think the model will be done soon.”

“I can’t wait to see it! All the photos Kohaku brought with her when she stopped by are so cute! Your face gets all pinched when you focus, Senku-chan.”

Senku huffs, shuffling some of the photos around in front of him. “Minami knows just how to capture my good side.” There are a lot of photos of him, mostly ones of him working, and some shots of the others playing around. He can spy Gen in the background of a few images, usually hovering at Senku’s side, but this batch only features one of Gen as the main subject, and Senku extracts it from the pile, tilting it to let the sunlight fall across the surface.

It’s a shot from a magic show Gen put on for the village kids a few weeks ago. He’s grinning theatrically, hands displayed and empty at his sides, surrounded by little, attentive heads. Senku can’t tell if Gen knew the camera was there or not, but it looks posed.

“These photos are an important resource,” Gen is lecturing in his ear. “A photographic record of the evolution of the new world!”

“And a good survey tool.”

Gen sighs. “That too.”

So far, this photographic record of the new world contains solo shots of nearly every major figure in the Kingdom. Senku can easily pick out candid singles of Kohaku, Chrome, Ryusui, Ukyo, Suika, Taiju, himself—and that’s just in this batch—but no pictures of Gen on his own. “Huh.”

“What was that, Senku-chan?”

“Nothing.” Senku lays the photo back on the table. “Anyway, how are things over there?”

“Great! As far as I can tell.” Senku can almost hear how Gen purses his lips. “I think it’s smart to make more antibiotics for the trip, but since Ruri-chan and I are relying on your instructions, it’ll be hard for us to troubleshoot if something goes wrong.”

“Don’t stress. We’ve got plenty of time. And if something happens, I’ll come over there.”

“Such a benevolent leader we have,” Gen teases. “The more we do it, though, the more I think I actually understand the process.”

“See? It’s not that difficult.”

“I never said that.”

“Just think of it like a magic trick.”

“Of course! Because all of my tricks involve thirty steps and multiple opportunities for catastrophic failure and _fire_.”

Senku snickers, but any retort he might concoct is cut off by a loud crash from outside the hut. Peering through the window, he sees several people rush toward the shipyard, shouting. “I’ve gotta go. I have to head to the mine tomorrow, but I’ll call next time I get a chance.”

“Roger that, chief!”

Senku hangs up and spares the photos one last look before hurrying outside.

Minami has an uncomfortably knowing glint in her eye when Senku subtly broaches the topic of photographing Gen later that day.

“That little bastard is surprisingly slippery,” she pouts, crossing her arms. “I try to give everyone equal attention, but he’s always with you. And when he’s not with you, he’s nowhere. He acts oblivious, but I think he’s doing it on purpose.”

“Why would he do that?”

She quirks an eyebrow. “How should I know? Aren’t you the one closest to him?”

Inexplicably, Senku feels his cheeks heat up. “I—”

“But I would have thought someone like Gen would _want_ to be in pictures,” Minami continues, twirling a strand of hair around her finger thoughtfully. “I never covered him back in the old days, but I saw him around. He certainly seemed like an attention hog.”

Senku hums, mind wandering.

“Anyway, I wouldn’t mind some shots of him!” Minami smiles brightly. “If you can get him to sit still long enough.”

“Yeah,” Senku responds absently, tapping his chin as an idea assembles itself in his head.

* * *

Senseeeeiiiiii  
  
Seeeensiiieie  
  
...yes?  
  
It’s you! You’re up!  
  
It’s only midnight. Are you okay?  
  
Yes I’m great  
  
Are you drunk?  
  
Wow you really do know everything sensei  
  
I might be  
  
tipsy  
  
Oh boy.  
  
Yeah yeah you act all begrudging but I know you like me  
  
Sure.  
  
You can’t pretend anymore plus you told me yourself  
  
Well, logically, I must like you at least a little to keep talking to you like this.  
  
Right!!  
  
It’s okay. I like you too  
  
I’m flattered.  
  
Sometimes I wish w  
  
e could meet  
  
I wish you were real  
  
I am real.  
  
You know what I mean  
  
I suppose I do.  
  
I’m crying  
  
Why? Is something wrong?  
  
I don’t know I’m just crying I’m  
  
it’s  
  
You’re my best friend sensei  
  
That’s sad  
  
It’s not sad.  
  
It is sad!!! You’re my best friend and I’ve never even met you and I never will  
  
We don’t know that for sure.  
  
Yeah we do  
  
If we wanted to we would have met already  
  
You’ve never mentioned any of this before.  
  
I can’t! If I tell you you won’t keep texting me!  
  
And when I think about it too hard I cry so I don’t think about it  
  
This isn’t how we talk to each other  
  
This is all wrong  
  
It’s not wrong.  
  
  
I just didn’t know you felt like this.  
  
Well I don’t  
  
I’m going to delete this chat so sober me doesn’t see it pls don’t mention it tomorrow  
  
If that’s what you want.  
  
You’re a good person sensei  
  
I’m glad we’re friends  
  
Yeah. Me too.  
  


* * *

Paradigm shifts are rare.

Throughout recorded history, there have only been so many moments that qualify as proper paradigm shifts, in that nothing that comes afterward will be the same as what came before. Events that forever altered thought and humanity’s understanding of how the world functions. The advent of agriculture, the industrial revolution, Darwin’s _On the Origin of Species_ , the first world war, Einstein’s theory of special relativity—and finding out that Gen is Ma-ban.

Senku is fully convinced that the revelation that occurred in that hot air balloon ranks among the most catalytic events of human history. As the most driving, sentient force present on Earth at the moment, anything that flips his worldview more than qualifies as paradigm-shifting.

It’s astounding. As Senku blinks awake to the sight of Gen’s tousled head on the pillow beside him, his _bones_ feel lighter, like he’s been hauling around a lead skeleton since the moment he broke out and only now is he free of the weight.

Tightening his grip around Gen’s waist, Senku noses at Gen’s bare nape, breathing in his light floral scent. Senku never thought of himself as the cuddly type, mostly because he never thought the opportunity would arise and didn’t much care either way, but something about Gen makes him want to cling.

Purring low in his chest, Gen shifts against him, and Senku feels a hand settle on his arm. “Someone’s friendly this morning,” comes Gen’s sleepy voice, half-muffled by the pillow. They’re curled up on the floor of the observatory, and the sunlight streaming in through the ceiling catches in Gen’s hair, glowing off the white half and glittering in the black half as a series of starry rivers.

“It’s cold.” Despite the chill of the air, the space between them is warm and Gen is a comfortable heat against Senku’s front, giving Senku a good reason to press closer, fitting their legs together under the blankets. “This place isn’t insulated like our hut.”

“True, but I like it more.”

Senku does too, but he puts the sentiment into a light brush of lips against the back of Gen’s neck. Gen bows his head forward with a hum, giving Senku more access, which Senku accepts readily, trailing kisses up to Gen’s ear before skimming his teeth over the delicate pink shell.

Gen giggles, hugging the arm Senku has wrapped around his middle. “I never thought you’d be this affectionate, Senku-chan.”

Pulling back, Senku uses his grip on Gen to roll him backward, until Gen is blinking sunny blue eyes up at him. “When I’m interested in something,” Senku murmurs, ducking down to speak against Gen’s temple, “I want to know everything.”

Gen shivers faintly. “I...I suppose that makes sense,” he says breathlessly, reaching up to snake his arms around Senku’s neck. “You’re a pretty confident guy, Senku-chan. No longer the awkward teenager I used to be so fond of.”

“Disappointed?”

“Maybe a little.” Gen sighs, carding one hand through Senku’s sleep-mussed hair as Senku nuzzles under his jaw. “You were so cute back then.”

“Get over it.”

“I guess you’re still pretty cute.” Framing Senku’s face, Gen guides his head back up to fix him with a teasing gaze. “I really should have realized it sooner. The way you speak, your sense of humor, your vast array of knowledge—there’s really no one else like you, Senku-chan.”

“Yeah, I’m insulted you thought there were _two_ inhumanly intelligent, space-obsessed Japanese high schoolers running around.”

“Silly me.”

Senku’s eyes drop to the curl of Gen’s mouth. “And I can’t believe I ever thought there was someone else like you in the world.” Jaw tightening, Senku pushes away, sitting up and letting the blankets fall away from his shoulders. “I really….”

Brows pulling together, Gen follows him up and draws the backs of his fingers down Senku’s arm. “What is it?”

Shaking his head, Senku braces one elbow on his knee, pressing his hand to his forehead. “I considered it sometimes, you know?” he admits. “Sometimes, you’d say something, or do something, and I would think…. _maybe_ —but the chances were so low...I didn’t want to let myself hope.”

Gen watches him patiently, settling his hand over Senku’s on the blanket between them.

“I thought I’d never find you,” Senku continues roughly. “If I actually believed it was you, and you weren’t...it would be like losing you all over again.” He lets out a bitter laugh. “I used to get so mad at myself for comparing you, but I couldn’t help it. You reminded me of them so much...and when I started relying on _you_ like I used to rely on Ma-ban….”

“You felt like you were betraying your friend,” Gen finishes softly.

“If I had just gotten over myself and asked you earlier, then I could have avoided all of this drama—for both of us—”

“Senku-chan, you can’t blame yourself.”

“But when have I ever hesitated to do something?”

“Feelings aren’t science.” Gen twists his mouth to the side. “To tell you the truth, I didn’t figure it out on my own. I was like you—sometimes, I _wondered_ , because you reminded me of Sensei so much that sometimes I thought it couldn’t possibly be a coincidence...but I didn’t want to face the disappointment of being wrong. Eventually, Yuzuriha-chan told me.”

That startles a snort out of Senku. “Of course she figured it out first. She was always so interested in my texting friend.”

“But this was months ago.” Gen averts his eyes. “After you built the balloon. I’ve...known since then. But even then, I was afraid to say anything.” He bites his lip. “I wasn’t sure if you’d still want me. We’re different people now, and I wondered if it would be better to just...move on. As different people.” He glances back at Senku, looking contrite. “I’m sorry for keeping it from you. Of course, I can understand why you’d be worried about your friend. I was worried about Sensei too. I shouldn’t have left you in the dark.”

For a beat, Senku holds his stare, and the observatory is quiet except for the restless twittering of birds in the surrounding trees. Then a smile quirks Senku’s lips. “We really are lucky.”

Gen blinks. “Lucky?”

“Two complete idiots who found each other _twice_.” Catching Gen by the hand, Senku tugs him closer, snagging him around the waist before he can react. “Yesterday, what did you say it was?”

Helplessly, Gen giggles against Senku’s mouth. “Fate? Destiny?”

“You might actually be onto something there.”

“How very illogical, Senku-chan.”

“Nothing about you is logical, mentalist.”

Gen laughs again, and they kiss like a puzzle falling into place, until Gen’s hands and voice and scent are the only things Senku can think about, filling his head with heat and light. He grabs Gen by the waist and topples him backward into the blankets, climbing over him, and the way Gen looks up at him, all sly blue eyes and pink cheeks, minimizes every tab in Senku’s brain at once, leaving nothing but the irrational desire to kiss Gen senseless.

Senku’s had Gen on his mind for more than 3700 years, and he doesn’t think that’s going to change anytime soon. He doesn’t want it to.

**Author's Note:**

> i hope that was worth the wait! 
> 
> come see me on [tumblr](https://mistresseast.tumblr.com/) or [twitter](https://twitter.com/MistressEast)! i'm on a bit of a p5 kick rn, but i still love dr. stone and keep up with the weekly updates. does anyone else think it's a little coincidental that Senku and (manga spoilers) Xeno were virtual pals who met up again in the stone world? hmmm sounds familiar..... lmao 
> 
> thank you all so much for the kind words and support. stay safe <3


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